buid a amp rack out of mdf and mount it to the trunk lid. mount the amp to the amp rack and run the wires. it is not that hard really just bad for most amps.

I cut a piece of plywood (i think around 3/8th thick) to the shape of the trunk....and carpeted it...I didn't use MDF because of the added weigh.

I screwed 2 small blocks in the middle, one top and one bottom....so the board would lie better. then i screwed the board down in the top middle,bottom middle(into those blocks) and to the bottom left and right.

Its real secure......i screwed into the rib supports of the trunk.
DO NOT SCREW ALL THE WAY THRU YOUR TRUNK...this could easily be done!